We've had it noted in two audits (we had to buy a special lock box for returned mail last year) and examiners always ask for our log. Yes, the reason is someone might send cash, and on the returned mail, for the "dual" control to shred the statements. It's a dumb thing, but if it keeps them occupied, I won't upset the apple cart. These are the same people that require we do a "Verification of Accounts" which is even more pointless since so many members have e-statements, and/or have ability to view accounts online. Verifications are expensive and time consuming and their usefulness has passed.